A definition of risk is an effect of uncertainty on objectives. Consequently, hazard must include clearly the uncertainty. Case studies of hazard identifi-cation in risk assessment for high pressure gas accidents are shown. Hazard scenarios comprise hazard, hazard situation and hazard event. Typical hazard scenarios in the three cases of human, physical and inter-face hazards are summarized.
This work presents an evaluation method of the dynamic pressure acting on the cylindrical liquid storage tank for the modified seismic coefficient method which is a foremost important seismic resistant design method. A sim-ple equation of motion for the seismic response of cylindrical tanks from a velocity potential flow and the shear beam approach was developed for examining combination methods of two kinds of dynamic pressures acting on the cylindrical tank shell; namely, the dynamic pressures induced by the rigid motion and it induced by the flexile deformation of the tank shell. The time history analyses using by the artificial seismic wave, which represent the design response spectrum in the modified seismic coefficient method, were conducted. As the results, a rational combination method of two kinds of dynamic pressures for evaluating the modified seismic coefficient method is presented. The evaluated dynamic pressures obtained by the pre-sented method are compared and discussed with the dynamic pressures ob-tained by the current seismic resistant design guideline, and the applicability of the presented method is demonstrated.
Galvanizing makes the surface of the steel products to prevent the corrosion on the steel surface, and to endure the long-term use of steel products. Generally, in galvanizing process, the steel product is dipped into the molten zinc with about 440 to 470°C then zinc coating with about 50 to 150 μm is formed on the surface of the steel material to achieve long-term corrosion protection. Recently, zinc coating steel structure is increasing in size therefore the size of molten zinc galvanizing bath also becomes larger and larger. In this report, some examples of corrosion and wear of steel galvanizing baths by molten zinc are introduced and the mechanism of corrosion and wear by molten zinc is described. In addition, the operation and management control of hot dip galva-nizing bath made of steel is discussed from the point of view of the prevention of corrosion and wear by molten zinc.
On October 9, 2018, a buried natural gas pipeline system “BC Pipeline” owned by Enbridge Inc. and operated by Westcoast Energy Inc. exploded in a forest area near Prince George, British Columbia, Canada. Fortunately, there were no residential houses in the vicinity and no one was injured. The Transportation Safety Board of Canada (TSB) which conducted the investigation published the final report on March 4, 2020. The cause of the accident was that the natural gas leaked from the ruptured pipeline due to near-neutral pH stress corrosion cracking and ignited. This paper describes the accident based on the TSB report.